HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 357

Example 10: First order linear differential equation, jump to the screen

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Example 10: First order linear differential equation In order to illustrate the use of the CAS help pages discussed on page 361 we will the example provided in them rather than making one up. The functions available for solving differential equations are DESOLVE and LDEC. Begin by pressing SHIFT SYNTAX to open the help menu and scroll down to the DESOLVE function as shown right. Pressing will jump immediately to the 'D's. Pressing ENTER will display the screen shown right. Notice the reference to LDEC at the bottom of the screen. Pressing will jump to the screen for LDEC. Press to paste the example into the CAS editing screen. The screen shot right has been obtained by pressing VIEWS and cutting and pasting in a Paint program to obtain a wider result. The 'd1Y(X)' is used to represent the first derivative. Highlighting this and pressing ENTER will give the result shown right. Note the use of 'cC0' to represent a constant. ( x −1) ex + c This is equivalent to y = ex . The CAS unfortunately uses EXP(X) to represent ex , although it will understand the use of ex when entering an expression. 357

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Example 10:
First order linear differential equation
In order to illustrate the use of the CAS help pages discussed on page 361 we will the example provided in
them rather than making one up.
The functions available for solving differential equations are
DESOLVE
and
LDEC
.
Begin by pressing
SHIFT SYNTAX
to open the help menu and scroll
down to the
DESOLVE
function as shown right.
Pressing
will
jump immediately to the ‘D’s.
ENTER
Notice the
will
VIEWS
d1Y(X)
’ is
Pressing
will display the screen shown right.
Press
to paste the example into the CAS editing screen.
The screen
shot right has been obtained by pressing
and cutting and
pasting in a Paint program to obtain a wider result.
The ‘
reference to
LDEC
at the bottom of the screen.
Pressing
jump to the screen for
LDEC
.
used to represent the first derivative.
Highlighting this and pressing
ENTER
will give the result shown
right. Note the use of ‘
cC0
’ to represent a constant.
x
This is equivalent to
y
=
(
x
1
)
e
+
c
.
The CAS unfortunately uses
e
x
x
x
EXP(X)
to represent
e
, although it will understand the use of
e
when entering an expression.
357